Grotto | partisans

Perched at the northwest edge of an island on Georgian Bay, the Grotto Sauna is a feat of old-world craftsmanship and newworld sustainability made possible by cutting-edge software and fabrication technology. It is a sculpted space, a sensual experience, and a sophisticated exercise in building science. Inspired by an Italian grotto—a secret water-fi lled cave concealed within unsuspecting rock formations—our design pays homage to the extremities of the Northern Ontario landscape.

To the extent that the objective was to tell an architectural story of escape and refuge, we conceived of a design that married contrasts to transport visitors into an otherworldly sanctum. A simple but dignifi ed exterior built from charred cedar prepared using the traditional Japanese Shu Sugi Ban method conveys a weathered appearance—it’s as if the building has been hidden in plain sight for centuries.

By contrast, the warm, curved interior emulates Lake Huron’s waves and mirrors the Precambrian shield—a soft, undulating rock surface that has been worn over billions of years. The luminous glow of the interior wood enhances the sunkissed sauna experience, while the pre-aged exterior veils the intimacy of that experience from the world. Importantly, the Grotto is a highly sustainable structure that established a successful methodology for addressing the challenges of building ambitious architecture in remote and environmentally sensitive regions.

The site was digitally scanned to create a highly accurate 3D model from which we could analyze and position the structure to minimize site impact, while retaining optimum views of the sunsets. We also worked directly with our fabrication partners on every detail to develop new prototyping and milling methods.